import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


// op: T * T -> T, associative
struct Queue(T, alias op) {
  import std.functional : binaryFun;
  alias opFun = binaryFun!op;

  int asLen, bsLen;
  T[] as, aas, bs, bbs;

  this(int n) {
    asLen = bsLen = 0;
    reserve(n);
  }
  void reserve(int n) {
    assert(asLen + bsLen <= n);
    as.length = aas.length = bs.length = bbs.length = n;
  }
  void reduce() {
    for (; bsLen != 0; ++asLen, --bsLen) {
      as[asLen] = bs[bsLen - 1];
      aas[asLen] = (asLen == 0) ? bs[bsLen - 1] : opFun(bs[bsLen - 1], aas[asLen - 1]);
    }
  }
  int size() const {
    return asLen + bsLen;
  }
  void push(T t) {
    insertBack(t);
  }
  void pop() {
    removeFront();
  }
  T get() {
    if (asLen == 0) reduce();
    assert(asLen != 0);
    return (bsLen == 0) ? aas[asLen - 1] : opFun(aas[asLen - 1], bbs[bsLen - 1]);
  }

  bool empty() const {
    return (asLen == 0 && bsLen == 0);
  }
  void clear() {
    asLen = bsLen = 0;
  }
  T front() {
    if (asLen == 0) reduce();
    assert(asLen != 0);
    return as[asLen - 1];
  }
  void insertBack(T t) {
    bs[bsLen] = t;
    bbs[bsLen] = (bsLen == 0) ? t : opFun(bbs[bsLen - 1], t);
    ++bsLen;
  }
  void removeFront() {
    if (asLen == 0) reduce();
    assert(asLen != 0);
    --asLen;
  }
}


void main() {
  try {
    for (; ; ) {
      const H = readInt();
      const W = readInt();
      const N = readInt();
      auto C = new int[][](H, W);
      foreach (x; 0 .. H) foreach (y; 0 .. W) {
        C[x][y] = readInt() - 1;
      }
      
      auto mxs = new int[N];
      mxs[] = -1;
      void ae(int u, int v) {
        if (u != v) {
          if (u > v) {
            swap(u, v);
          }
          chmax(mxs[v], u);
        }
      }
      foreach (x; 0 .. H) foreach (y; 0 .. W) {
        if (x > 0) ae(C[x - 1][y], C[x][y]);
        if (y > 0) ae(C[x][y - 1], C[x][y]);
      }
      debug {
        writeln("mxs = ", mxs);
      }
      
      auto queEdge = Queue!(int, max)(N);
      auto queCost = Queue!(int, min)(N);
      auto dp = new int[N + 1];
      queCost.push(dp[0] = 0);
      int l;
      foreach (u; 0 .. N) {
        queEdge.push(mxs[u]);
        for (; l <= queEdge.get; ++l) {
          queEdge.pop;
          queCost.pop;
        }
        debug {
          writefln("[%s, %s]", l, u);
        }
        dp[u + 1] = queCost.get + 1;
        queCost.push(dp[u + 1]);
      }
      debug {
        writeln("dp = ", dp);
      }
      
      writeln(dp[N]);
    }
  } catch (EOFException e) {
  }
}